[PATCH 3.2 70/77] net: add validation for the socket syscall protocol argument

Ben Hutchings
2015-12-24T15:43:21Z

From: Hannes Frederic Sowa <hannes@stressinduktion.org>

[ Upstream commit 79462ad02e861803b3840cc782248c7359451cd9 ]

郭永刚 reported that one could simply crash the kernel as root by
using a simple program:

int socket_fd;
struct sockaddr_in addr;
addr.sin_port = 0;
addr.sin_addr.s_addr = INADDR_ANY;
addr.sin_family = 10;

socket_fd = socket(10,3,0x40000000);
connect(socket_fd , &addr,16);

AF_INET, AF_INET6 sockets actually only support 8-bit protocol
identifiers. inet_sock's skc_protocol field thus is sized accordingly,
thus larger protocol identifiers simply cut off the higher bits and
store a zero in the protocol fields.

This could lead to e.g. NULL function pointer because as a result of
the cut off inet_num is zero and we call down to inet_autobind, which
is NULL for raw sockets.

kernel: Call Trace:
kernel: [<ffffffff816db90e>] ? inet_autobind+0x2e/0x70
kernel: [<ffffffff816db9a4>] inet_dgram_connect+0x54/0x80
kernel: [<ffffffff81645069>] SYSC_connect+0xd9/0x110
kernel: [<ffffffff810ac51b>] ? ptrace_notify+0x5b/0x80
kernel: [<ffffffff810236d8>] ? syscall_trace_enter_phase2+0x108/0x200
kernel: [<ffffffff81645e0e>] SyS_connect+0xe/0x10
kernel: [<ffffffff81779515>] tracesys_phase2+0x84/0x89

I found no particular commit which introduced this problem.

CVE: CVE-2015-8543
Cc: Cong Wang <cwang@twopensource.com>
Reported-by: 郭永刚 <guoyonggang@360.cn>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: open-code U8_MAX]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/net/sock.h | 1 +
net/ax25/af_ax25.c | 3 +++
net/decnet/af_decnet.c | 3 +++
net/ipv4/af_inet.c | 3 +++
net/ipv6/af_inet6.c | 3 +++
net/irda/af_irda.c | 3 +++
6 files changed, 16 insertions(+)

--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -302,6 +302,7 @@ struct sock {
sk_no_check : 2,
sk_userlocks : 4,
sk_protocol : 8,
+#define SK_PROTOCOL_MAX ((u8)~0U)
sk_type : 16;
kmemcheck_bitfield_end(flags);
int sk_wmem_queued;
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -806,6 +806,9 @@ static int ax25_create(struct net *net,
struct sock *sk;
ax25_cb *ax25;

+ if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+ return -EINVAL;
+
if (!net_eq(net, &init_net))
return -EAFNOSUPPORT;

--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -681,6 +681,9 @@ static int dn_create(struct net *net, st
{
struct sock *sk;

+ if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+ return -EINVAL;
+
if (!net_eq(net, &init_net))
return -EAFNOSUPPORT;

--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -279,6 +279,9 @@ static int inet_create(struct net *net,
int try_loading_module = 0;
int err;

+ if (protocol < 0 || protocol >= IPPROTO_MAX)
+ return -EINVAL;
+
if (unlikely(!inet_ehash_secret))
if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
build_ehash_secret();
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -109,6 +109,9 @@ static int inet6_create(struct net *net,
int try_loading_module = 0;
int err;

+ if (protocol < 0 || protocol >= IPPROTO_MAX)
+ return -EINVAL;
+
if (sock->type != SOCK_RAW &&
sock->type != SOCK_DGRAM &&
!inet_ehash_secret)
--- a/net/irda/af_irda.c
+++ b/net/irda/af_irda.c
@@ -1106,6 +1106,9 @@ static int irda_create(struct net *net,

IRDA_DEBUG(2, "%s()\n", __func__);

+ if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+ return -EINVAL;
+
if (net != &init_net)
return -EAFNOSUPPORT;